1. Field of the Invention
The present invention relates to a structure for supporting a driving reaction force acting upon a differential housing of a forklift of the type having an engine and a transmission separated from the differential housing.
2. Description of the Related Art
In a forklift as shown in FIG. 5 where a transmission 2 linked with an engine 1 and a differential housing 3 are located separately from each other in the longitudinal direction of the vehicle, an output shaft 4 of the transmission 2 and a pinion shaft 5 of the differential gear are connected to each other by a propeller shaft 7 through universal joints 6. Such a transmission system with a separately located differential has an advantage that less vibration is transmitted from the engine 1 compared to a system of the type where the transmission 2 and the differential 3 are directly connected to each other.
Supporting structure for the differential housing 3 in a conventional separated-differential type transmission system is shown in detail in FIGS. 6 and 7. The differential housing 3 is rotatably provided between the transversely spaced apart, longitudinally extending frame members 8 of the vehicle, between the left and right front axle brackets 9 which are firmly fixed to the frame 8 of the vehicle. Thus, in order to prevent rotation of the differential housing 3 as it receives a driving reaction force when the driving force from the transmission is transmitted through the propeller shaft 7, a carrier cover 10 linked with the differential housing 3 is coupled to the left and right front axle brackets 9, respectively, by horizontally provided reaction force receiving bolts 11. In other words, the reaction force to driving is borne by the shearing force of the reaction force receiving bolts 11 which are provided at two locations.
Considering that, due to the multiple effects of tolerances of respective component parts, a shift in relative positions of the holes for receiving a reaction force receiving bolt formed respectively on the carrier cover 10 and the front axle bracket 9, the reaction force receiving bolt hole of each front axle bracket 9 is made somewhat larger than the outer diameter of the reaction force receiving bolt 11. For this reason, to prevent play between the reaction force receiving bolt 11 and the front axle bracket 9, the reaction force receiving bolt 11 is fixed with respect to the front axle bracket 9 by a fixing bolt 12. Further, in order to adjust a gap due to dimensional tolerance in the horizontal direction between the front axle bracket 9 and the carrier cover 10, an annular shim 13 as shown in FIG. 8 is inserted into such gap and the reaction force receiving bolt passes through and is tightened via a through hole 13a of the shim 13.
As described above, since the left and right front axle brackets 9 and the carrier cover 10 are coupled, respectively, by the reaction force receiving bolts 11, it has been necessary to set a strict machining tolerance to match the position of the holes for the reaction force receiving bolt. Since the reaction force receiving bolt 11 is provided in the horizontal direction, positioning of the holes for the reaction force receiving bolt at the time of assembly is not easy and makes the assembling operation difficult. Also, it is necessary to fix the reaction force receiving bolts 11 on both sides, respectively, by the fixing bolts 12, to prevent play between the reaction force receiving bolt 11 and the front axle bracket 9. The number of component parts is thereby increased and the structure becomes more complicated. Further, since the gap between the front axle bracket 9 and the carrier cover 10 is to be adjusted by the annular shim 13, the reaction force receiving bolt 11, which has once been tightened, must be pulled out to insert the shim 13 for the adjustment and then the reaction force receiving bolt 11 is tightened again. Time and labor are required for the correction of a gap.